Device for processing sheet copying material

ABSTRACT

APPARATUS FOR DEVELOPING SHEET MATERIAL CARRYING A RECORDING LAYER WHICH IS IRREVERSIBLY IMAGEWISE DIFFERENTIATED IN TERMS OF SOLVENT SOLUBILITY IN WHICH THE SHEET MATERIAL IS APPLIED TO A WETTED ENDLESS BELT AND IS DELIVERED THEREBY INTO FRICTIONAL RUBBING CONTACT WITH A ROTATABLE RUBBING DRUM HAVING A RESILIENT POROUS PERIPHERAL SURFACE. THE RUBBING DRUM IS WETTED WITH THE SOLVENT WHILE MAKING CONTACT WITH THE SHEET MATERIAL, AND THE PERIPHERAL SPEED OF THE DRUM IS PREFERABLY SUBSTANTIALLY HIGHER, SAY AT LEAST TEN TIMES HIGHER, THAN THE TRANSPORT SPEED OF THE SHEET MATERIAL ON THE BELT. SURPLUS SOLVENT CAN BE CAUGHT BETWEEN A TRAY ARRANGED BENEATH THE RUBBING DRUM AND THROUGH WHICH THE LOWER STRETCH OF THE ENDLESS BELT PASSES. ALL OF THE OPERATIVE COMPONENTS CAN BE ARRANGED WITHIN A HOUSING AN INLET AND OUTLET OPENINGS THEREIN FOR THE INGRESS AND EGRESS OF THE SHEET MATERIAL.

Feb. 1971 E. F. STIEVENART ETAL 3,562,834

DEVICE FOR PROCESSING SHEET COPYING MATERIAL 3 Sheets-Sheet 1 Filed Nov. '50, 1967 INVENTOR ML -S 'im m when.

ATTORNEY 1971 E. F. STIEVENART ETAL DEVICE FOR PROCESSING SHEET COPYING MATERIAL Filed Nov. 30, 1967 3 Sheets-Sheet 2 m QM Feb. 16, 1971 3,562,834

DEVICE FOR PROCESSING SHEET COPYING MATERIAL Filed Nov; 30, 1967 E. F. STIEVENART ETYALV 3 Sheets-Sheet 5 INVENTOR BY 90M, M,

United States Patent 3,562,834 DEVICE FQR PROCESSING SHEET CQPYING MATERIAL Emile Frans Stievenart, Antwerp, and Marcel Nicolas Vranclren, Hove, Belgium, assignors to Gevaert Agfa N.V., Mortsel, Belgium, a Belgian company Filed Nov. 30, 1967, Ser. No. 686,882 Claims priority, application Great Britain, June 2, 1967, 25,646/ 67 Int. Cl. 603d 5/06 U.S. Cl. -100 8 Claims ABSTRACT OF THE DISCLOSURE Apparatus for developuing sheet material carrying a recording layer which is irreversibly imagewise differentiated in terms of solvent solubility in which the sheet material is applied to a wetted endless belt and is delivered thereby into frictional rubbing contact with a rotatable rubbing drum having a resilient porous peripheral surface. The rubbing drum is wetted with the solvent while making contact with the sheet material, and the peripheral speed of the drum is preferably substantially higher, say at least ten times higher, than the transport speed of the sheet material on the belt. Surplus solvent can be caught between a tray arranged beneath the rub bing drum and through which the lower stretch of the endless belt passes. All of the operative components can be arranged within a housing having an inlet and outlet openings therein for the ingress and egress of the sheet material.

The present invention relates to a device for processing sheet copying material of the type which on image-wise exposure to high intensity radiant energy exhibits an irreversible differentiation in solubility.

Material of the mentioned kind is known, e.g., from the published Dutch patent applications 6414226, 6606719 and 6700359. In the specifications thereof a material is described comprising at least one recording layer having incorporated therein particles composed substantially of a hydrophobic thermoplastic polymer, said layer consisting of a dispersion of said particles in a hydrophilic binder. The material is imagewise heated by exposure to high intensity radiant energy, whereby a recording is formed in said layer in terms of a difference in solubility and/or lyophility and/or meltability. In case it is intended to make use of the property of the differentation in solubility, in order to produce a copy or a master, the processing of the material leads to the removal of the parts of the material which have been less heated or not at all heated and which consequently remained more soluble after the exposure.

The object of the present invention is to provide a device for processing the described copying material after the imagewise heating wherein the soluble parts of the material are removed.

According to the present invention, the device for processing sheet copying material of the type which when image-wise heated exhibits an irreversible differentiation in solubility, comprises means for transporting said sheet material through said device, rotatable rubbing means arranged to put a resilient and porous surface in smooth rubbing contact with the transported sheet material and supply means for providing processing liquid at least at the location where the rubbing means contacts the transported sheet material, the rubbing between the rubbing means and the sheet material being adjusted to selectively wash away only the more soluble parts from said material.

Preferably, the relative speed between the rubbing means and the sheet material is considerably greater than the transport speed of the sheet material through the device.

The term sheet material used in the present description, applies to material in the form of square or rectangular sheets, as well as to material in the form of strips, or even webs.

The term copying material includes, besides material which after processing yields the desired reproduction of the original to which it was exposed, either as a positive or a negative, also material which after processing constitutes a planographic printing master, the remaining non-soluble portions of the recording layer thereof are ink-receptive, or capable of being made so, so that a plurality of copies may be printed in using same.

The mentioned differentiation in solubility of the material does not exclude differentiations in other respects of the material, e.g. diiferentiations in lyophility, meltability, or permeability which, however, for the present application are not essential.

The means for transporting the sheet material through the device according to the present invention may comprise a plurality of driven pressure roller pairs, but they may comprise also a driven endless belt onto which the sheet is supported with the backside past the rubbing means during its travel. In a preferred arrangement the belt is wetted before the sheet material is located thereon, and the belt and the sheet lying thereon are sandwiched between a driven pressure roller pair before the exposed side of the sheet is engaged by the rubbing means. The small quantity of liquid remaining between the backside of the sheet and the belt is responsible for the good adherence of the sheet to the belt so that there is little risk for the sheet movement to become uncontrolled when the sheet enters in rubbing engagement with the rubbing means.

The rotatable rubbing means is preferably in the form of a rotatable roller which has a peripheral layer of a resilient and porous material.

The invention will be described hereinafter by way of example with reference to the accompanying drawings in which:

FIG. 1 is a diagrammatic view of the processing device according to the invention;

FIG. 2 is a view on line 22 of the processing device according to FIG. 1;

FIG. 3 is a diagrammatic View of an other embodiment of the device;

FIG. 4 is a diagrammatic view of a further embodiment of the device.

The device shown in FIG. 1 is mounted in a housing 10 which has an inlet opening 11 and an outlet opening 12 for the introduction and removal of the copying material.

The transport mechanism for transporting a sheet through the housing comprises the roller pairs 13, 14-15, 16 and 17, 1S and the guide plates 19, 20, 21 and 22. The rollers .13, 15 and 17 are directly driven by means of timing belts running over pinions provided at one extremity of the roller shafts (not shown). The opposite rollers 14, 16 and 18 are driven through peripheral contact with the directly driven rollers. To this end, the bearings of the shafts of rollers 14, 16 and 18 are mounted for slight displacement in respect of the driven rollers, and they are spring-biased towards said rollers. The rollers are provided with a resilient covering such as butyl-rubber.

The rubbing roller 23 comprises a hard plastic core which is provided with a resilient and porous covering 24- consisting of Perlon (registered trademark) foam. The covering was applied to the roller in helicoidally Winding (FIG. 2) a strip of such material, having a cross-section of about 1 x 1 cm., around the roller and in fitting it thereto by means of an adhesive.

Below roller 23 is provided a self-adjusting free-rotatable backing roller 25 with an undeformable periphery. The shaft extremities of the roller are vertically displaceable in recesses 26 of the bearings 27. The shaft extremities are supported by a yoke 28 which is fulcrumed by the support 29. The support 29 is fitted to a lever 32 which is pivotable round a pivot 30, and the height of which may be adjusted by means of the adjustment screw 31 which is provided with a knurled knob which projects through the frontside of the device. The fulcrumed supporting or backing roller 25 ensures the uniformity in pressure between the rollers 23 and 25, whereas the magnitude of said pressure is controlled by the adjustment screw 31.

In the operation of the device, the backing roller was so adjusted that, when no sheet was present between the rollers, the backing roller slightly impressed the resilient covering of the rubbing roller, say over a distance of 1 to 2 mm.

An elongate nozzle 45 which extends transversely of the path followed by a sheet in the device is located adjacent to the roller 23 and directs a layer of water to the nip between rollers 23 and 25. The nozzle is connected through a conduit 49 with a water supply, not shown. A curved plate 46 surrounding the greater upper part of roller 23 prevents water from being sprinkled throughout the device by the roller 23 rotating at relatively high speed. The supplied Water flows through the opening in guide plate 19, through which projects the backing roller 25, to the sloping plate 47 and is carried off through the conduct 48.

The transport roller pairs 13, 1415, 16 and 17, 18 were driven at a peripheral speed of 2.6 cm./ sec. whereas rubbing roller 23 and backing roller 25 were rotated at a peripheral speed of 173 cm./sec.

A blower 37 is located in a cylindrical housing 38, the exit of which is connected through a plenum 39 with a lateral opening in the box-like structures 41 and 42 which are fitted to the outside of the guide plates 21 and 22. Through a plurality of openings 43 a forced air current is produced in this way in the space between the two guide plates.

A sheet of copying material suited for processing in a device according to the present invention is prepared as follows:

A polyethylene terephthalate support provided with a subbing layer for gelatin is coated with the following composition pro rata of g. per sq.m.:

10% aqueous gelatin solution 400 aqueous dispersion of polyethylene having a particle size of less than 0.1 and an average molecular Weight comprised between 15,000 and Water 24O 10% aqueous saponine 40 3% aqueous solution of the sodium salt of the condensation product of oleic acid and methyltaurine 40 4% aqueous formaldehyde 20 4 The interlayer thus obtained is dried at 30 C. On this layer a black-coloured heat-sensitive layer is coated pro rate of 30 q. per sq.m. from the following composition:

10% aqueous solution of polyvinyl alcohol 45 40% aqueous dispersion of polyethylene as described above 60 Water 320 Aqueous carbon dispersion containing per g. 53 g. of carbon (average particle size 0.1 23 g. of water, 18 g. of glycol and 6 g. of nonylphenyl polyethylene oxide 3% aqueous solution of the sodium salt of tetradecyl sulphate 25 The device was operated as follows:

The sheet of copying material was exposed in contact to a negative transparency. The exposure was carried out in locating the transparency and the copying sheet in contact around a glass cylinder of a diameter of about 8 cm. In the axis of the cylinder a xenon gas discharge tube was provided, which produced a light energy of 1000 Joules, in a time of sec.

The exposed sheet of copying material was processed d as follows in the washing-day device.

The image-wise exposed copying sheet is inserted into the processing device through the inlet opening 11, the exposed heat-sensitive layer being turned upwardly.

The leading edge of the sheet presses the lever 50 of microswitch 51 downwardly, so that the electrical contact controlling the motors of the transport mechanism and of the blower is closed. A temporizing relay (not shown) keeps the electric circuit closed after the trailing edge of the sheet has passed beyond the lever of the microswitch, to ensure the continued working of the device until the sheet has left the exit opening 12.

The rubbing roller 23 which rotates at relatively high speed is provided with a continuously renewed water supply from nozzle 45, and smoothly washes away the portions of the black-coloured heat-sensitive layer of the sheet which have not been exposed and which consequently have not become insoluble.

After washing, the sheet is passed between the rollers 15, 16 which squeeze away excess of processing liquid. Next, the sheet is passed between the guide plates 21 and 22, where the forced air stream completes the drying of the sheet.

At the exit of the drying zone the sheet is gripped by the rollers 17, 18 and is further deflected by the roller 53 to move the sheet outside the device through the exit opening 12.

The sheet is dry or almost so when it leaves the device and it shows a positive transparent copy of the negative to which it has been exposed.

Although the adjustment of the backing roller 25 by means of the adjustment screw 50 depends on the type of material treated in the apparatus, its setting is not very critical, and practice proves that a readjustment is seldom necessary. The balanced mounting of the roller is further responsible for the excellent uniformity of the washing effect in the direction transverse to the sheet transport direction.

According to a modified embodiment, the driving of the transport rollers 13, 14-15, 16 and 17, 18 may occur through one motor, whereas the rotation of the rubbing roller 23 may be performed through another motor. The entering of a sheet actuates the microswitch 51 whereby the rollers are started to rotate as described hereinbefore. When the trailing edge of the sheet has passed the lever of the microswitch and the latter returns into its initial position, a delay mechanism keeps the motor of the transport rollers rotating during the time necessary for moving the sheet through the device, whereas the rotation of the motor driving the roller 23 is reversed. In this way, a pulling force is applied to the trailing portion of the sheet as it passes between the rollers 23, 25 so that there is no risk for the trailing part of the sheet comprised between the roller pairs 23, 25 and 15, 16 to become buckled by the rollers 23 and 25, rotating at a higher peripheral speed than the transport rollers 15, 16.

Another embodiment of the processing device according to the invention is diagrammatically shown in FIG. 3. It generally comprises the transport roller pairs 60 to 64 and the rubbing rollers 65, 66, all driven through conventional transmission means (not shown) by a motor 69. The rollers 65 and 66 are driven at a peripheral speed which is about times greater than the peripheral speed of the transport roller sets 60 to 64. The rollers 65 and 66 are provided with cooperating free rotatable backing rollers 67 and 68. The backing rollers are at either side journalled in a vertically displaceable bearing. At either side of the rollers the bearings are controlled by pivotable levers such as the levers 70, 71 which in their turn are controlled by an adjustment screw 72 operable from the front side of the device.

The rubbing rollers 65 and 66 comprise a hollow core which communicates through openings in its periphery with a resilient covering of porous material.

The backing rollers have a covering of a hard material e.g. polyvinylchloride.

Washing water, e.g. tap water, is supplied through a conduct 75 which communicates through appropriate sealing means with one end of the hollow cores of the rollers 65 and 66. The opposite ends of the cores are closed.

The flow of the water supply is adjusted to provide a sufiicient excess of water to ensure the convenient washing of the material when the material is slightly pressed against said rollers 65 and 66 by the backing rollers 67 and 68.

Water containing the washed out portions of the material is collected on the bottom of the device, and is carried oif through conduct 76.

The various parts of the device are made from plastics and stainless steel so that water droplets distributed in the device cannot cause any damage.

In the operation of the device, the operator starts the device by means of switch 77, so that motor 69 is made to rotate and a valve 81 controlling the admission of water to the conduct 75 is opened.

The exposed sheet material to be processed is slid into the device in the direction indicated by the arrow 78, and is transported in an uninterrupted movement through the device. The quickly rotating rollers 65 and 66 smoothly wash away the soluble portions of the heat-sensitive layer of the material.

Excess of processing solution is squeezed off by the roller pairs 62 and 63, whereafter the sheet is returned by the rollers 64 so that it finally slides downwardly over the desk plate against the abutment member 80. Thereafter the device may be switched olf, whereby the rollers become inoperative and the valve 81 is closed.

An improved embodiment of the device according to the invention which shows some interesting aspects over the foregoing devices, is described hereinafter in connection with FIG. 4.

The device is located in a housing 90, and has an inlet opening 91 and an outlet opening 92 for the sheet material, and a switch 93 for controlling the operation of the device.

An endless rubber belt 94, the width of which corresponds about with the length of the inlet opening 91 is tensioned over idler rollers 95, 96, 97 and 117, and is driven by the pressure roller pair 98, 99. The said roller pair, as well as the outlet squeegee roller pairs 100, 101, and 102, 103' are driven at equal speed by a motor 104 through conventional transmission means (not shown). The belt portion extending between rollers 1117 and 97 is directed in such a way that a web lying thereon is directed towards the nip of rollers 100, 101.

The rubbing roller 105 has a covering 106 of resilient porous foam, which is several times thicker than the diameter of the metal core of said roller so that said covering is considerably impressed by the contact with the endless belt to provide a contact surface which extends over about 2 cm. in the advance direction of the endless belt. The roller 105 is driven by a motor 107 in anti-clockwise direction.

A tray 108 is provided in the device so that it can collect all of the water which drips from the endless belt and from the squeegee rollers at the exit opening. The tray has an outlet 110 through which the water contained therein flows through a conduct 111 to a pump 112, the outlet 113 of which is connected through a conduct, not shown, to a nozzle 114. The nozzle 114 is a metal tube which extends transversely of the device and which is arranged for directing through a longitudinal slit a fine layer of water in the direction of the arrow 115 towards the endless belt.

In normal operation the tray 108 is filled to the level indicated by the dash and dot line 116.

When a sheet to be processed is introduced through the opening 91, and the switch 93- is closed so that motors 104, 107 and the pump 112 are started to operate, the sheet becomes positively driven as its leading margin enters the nip between the pressure rollers 98, 99.

When the sheet enters said nip, the liquid which amply adheres to the endless belt is squeezed away, so that only a very thin layer of liquid is left which is responsible for the good adherence of the sheet to the belt. As the sheet approaches the rapidly rotating rubbing roller, its exposed upper side becomes abundantly wetted by the water sprayed thereon from the nozzle 114.

When the sheet passes under the rubbing roller, the soluble portions of the sheet material are gently rubbed away. During this rubbing operation the sheet transport remains unaffected since the adherence of the backside of the sheet to the belt is much greater than the frictional forces applied to the frontside of the sheet.

At the moment the sheet reaches the roller 97, the endless belt is sharply curved around the said roller. The adherence of the sheet to the belt is insuflicient for following the sharp curvature, so that the sheet separates from the belt and is directed between the squeegee roller pairs 100, 101 and 102, 103. Some tens of seconds after leaving the device, the sheet is dry.

In the described device the water supply was sufficient for processing many hundreds of sheets.

In the case of a device which is extensively used, means may be incorporated in the apparatus which is responsive to the level the liquid takes in the tray, so that a warming signal may be automatically operated in case an insufficient working of the rubbing roller is to be expected.

In the described device and when processing materials of the type described hereinbefore, the washed out portions of the sheets, which remained in the processing liquid, were not detrimental to the processing of next sheet. When these portions would cause difficulties indeed, a filter element may be inserted in the conduct to or from the pump so that they may be continuously removed from the processing liquid.

The device according to the present invention may also be used for processing materials which on image-wise exposure to heat exhibit an irreversible differentiation in solubility but wherein, contrary to the materials known from the references cited in the introductory part of the description, the more soluble portions of the recording layer are formed at the areas which have become heated on image-wise exposing. Such material comprises e.g. a layer mainly consisting of gelatin, wherein pigment substances, which absorb visible light and convert it into heat, are non-differentially distributed. The material is exposed to an original with which the gelatin layer does not stand in heat-conductive relationship. Said material is described in our published Dutch patent application The device according to the invention is not limited to the described embodiments. The washing operation need not necessarily occur by means of water as described hereinbefore.

In fact, the composition of the copying material may be such that the washing occurs, e.g., by means of alcohol or a mixture of alcohol and water. In this case, the washing operation preferably occurs in a closed circuit as described hereinbefore in connection with FIG. 4.

In case a particularly intensive washing is desired, two or more rotatable rubbing means may be provided. Materials other than the Perlon foam described hereinbefore may be used, of synthetic or natural structure, provided they are sufiiciently resilient and show a porous surface.

The control of the rotation of the rubbing roller may occur through a separate microswitch or sensing device so that said roller is rotated only when a sheet is pressed thereto.

Finally, the device may be incorporated in automatic apparatus, including an exposure station, and a feed station for feeding copying material from a stacker a roll of such material to the exposure station as an original is introduced into the apparatus, and for returning the original after the exposure and for directing the exposed sheet of copying material to the processing station.

We claim:

1. Apparatus for processing sheet copying material comprising a recording layer which exhibits an irreversible image-wise differentiation in solubility in a solvent, comprising a housing having an inlet and an outlet opening, and within said housing an endless belt for transporting a said sheet material from said inlet towards said outlet opening, rotatable rubbing means with a resilient porous surface so disposed as to make frictional rubbing contact with the recording layer of the sheet transported on said endless belt, means for Wetting said rotatable rubbing means with said solvent, means for wetting said endless belt With said solvent, pressure means disposed upstream of said rotatable rubbing means for urging an introduced sheet firmly onto said wetted endless belt prior to the engagement of the sheet by said rubbing means,

means for driving said endless belt, and means for driving said rotatable rubbing means at a peripheral speed which is substantially greater than the transport speed of the endless belt.

2. Apparatus according to claim 1, wherein the rubbing force between the rotatable rubbing means and the sheet material supported on the endless belt is so adjusted that the sheet and the rubbing means are in contact over a distance of at least 0.5 cm.

3. Apparatus according to claim 1, wherein a further pressure means is disposed downstream of said rotatable rubbing means.

4. Apparatus according to claim 1, wherein said pressure means is formed by an idler roller which is subtended over an angular path of its periphery by said endless belt.

5. Apparatus according to claim 1, wherein said means for Wetting said endless belt is formed by a tray which may be filled with liquid up to a level so that the endless belt runs over the lower part of its path through said liquid.

6. Apparatus according to claim 1, including control means causing the rotatable rubbing means and/or the transport means to rotate in response to insertion of a sheet material into said inlet opening.

7. Apparatus according to claim 1, including means for accelerating drying of the sheet material after passage through said rubbing means.

8. Apparatus according to claim 1, wherein said rub bing means is rotated at a peripheral speed ten times greater than the transport speed of said belt.

References Cited UNITED STATES PATENTS 1,930,575 10/1933 Wynd et al. 34148 2,305,011 12/1942 Kienninger 15-100 3,304,566 2/1967 Doerschlag 15-40 3,333,291 8/1967 Hondzinski 1540 CARLTON R. CROYLE, Primary Examiner H. B. RAMEY, Assistant Examiner I US. Cl. X.R. 

